Booster pumps can be used to increase your water pressure for your whole house or just your shower. The 2 main leading brands are SALAMANDER and STUART TURNER. Care must be taken when choosing the right pump for your water system. This link from the Stuart Turner website gives a description on which pump would be suitable to boost your shower.
If you do not have a cold water tank then your only option would be the pump in this youtube clip.
[youtube height=”” width=””]https://www.youtube.com/watch?v=KamDatuI-eo[/youtube]
You also need to be aware not all showers are designed for high water pressure, therefore your shower may also need replacing if you install a high pressure booster pump.
You can also by power showers where the pump is in the shower unit, which means you have what looks like a large electric shower like the picture below. Installing this type of power shower on a stud wall is not advised due to the noise created when the pump is running.